How to Make Castile Soap at Home

Make Castile Soap

There are few things in life more satisfying than being able to make your own products at home and put them to use. Knowing what goes into the item that your using helps you to steer clear of any unwanted ingredients; making the item yourself also allows you to add any personal touches that you may desire. When beginning to make household products at home, one of the easiest and most useful that you should consider is castile soap.

Castile soap is named after Castilia, or the Castile region in Spain, where the soap was first produced. It’s a slow-lathering soap and is quite hard, but it is also known to be quite gentle. Supposedly, it is also used by many as a first soap for their young children.

Soap 300x244 How to Make Castile Soap at Home

How to Make Castile Soap at Home


Before you begin making your soap, you’ll need a few basic items. All of the items should more or less be used exclusively for soap making, as some of the ingredients in the soap making process can be quite harsh by themselves. To make your soap, you’ll need:

  • 1 1-gallon or larger stainless steel or enamel pot
  • 2 plastic or glass pitchers (2-3 qt. size)
  • 1 2-3 cup measuring cup
  • 1 wooden or plastic spoon for mixing, or 1 stick blender
  • 2 wooden or plastic spoons
  • 2 thermometers (1 meat and 1 candy, or 2 heavy-duty kitchen thermometers)
  • 1 plastic container with snap-on lid (8″ x 11″ x 3″ or larger) or soap mold
  • Rubber gloves, safety goggles

Once you’ve collected all of your soap-making equipment, it’s time to get your ingredients. For basic castile soap, you’ll need:

  • 12 oz. lye crystals (be very careful when handling lye)
  • 24-32 oz. cold water (the more water, the longer it takes to firm up)
  • 48 oz. 100% pure olive oil (not virgin)
  • 16 oz. coconut oil
  • 16 oz. palm oil

To begin making your soap, put on your rubber gloves and safety goggles and measure out 12 oz. of lye crystals into one of your plastic pitchers. Weigh out 32 oz. of water into the other container, slowly pouring in the lye crystals and stirring until dissolved. Take care not to splash the water as you add the lye or stir; lye can be caustic. Be sure to always mix it in a well-ventilated area.

The lye mixture will be quite hot, so take care when working with it… let the temperature reduce to around 95-100 degrees before working with it again. While the lye cools, mix your oils and begin to heat them in your soap-making pot until they reach that same temperature range. If the lye is still too hot, you may place the container into another container of cold or ice water to reduce the temperature as needed.

Once your oils and lye mixture are both within the proper temperature range, begin slowly pouring the lye mixture into the oils, stirring continuously with either a spoon or the stick blender. Once all of the lye has been added and mixed, you’ll see the mixture begin to thicken. Continue stirring until a visible track is seen on the top of the soap (known as tracing). Tracing can take anywhere from a few minutes to the greater part of an hour, depending upon the temperature of your soap mixture.

Once tracing occurs, pour the soap mixture into your container or soap mold. Once you’ve filled the container, put the lid onto it, or if using a mold place a large piece of cardboard on top of it. If the soap mixture doesn’t fill the container completely, place a sheet of freezer paper on top of the mixture before putting on the lid.

Wrap the container in blankets and place them inside of a black plastic bag, placing it in a location where it can lay undisturbed for around 18 hours. The temperature of the soap mixture will be beginning to rise as the lye and oils continue to combine to make soap; the blankets help to hold in the heat so that the reaction will continue for as long as possible. Once 18 hours have passed, remove the blanket and bags and leave the soap alone for another 12 hours.

Once the 12 hours have passed, you should have a large, hard block of soap that can be removed from the container or mold. If the soap still seems to be a bit soft, let it sit for a day before working with it; if it is hard, go ahead and slice it into bars or chunks immediately. Place the bars or chunks into an open box or onto a drying rack, not letting the bars touch, and allow it to cure for at least 2 weeks. The longer the soap cures, the milder it will be; many soap makers allow their bars to cure for at least 4-6 weeks before using them.

For variations on this recipe, use 2-4 oz. beeswax in place of some of the coconut and palm oil, or remove the palm half of the olive oil and replace with vegetable shortening. To slow the thickening of the mixture, add soybean oil in with your oils (around 16 oz.); slowing the thickening can also make swirling the soap easier.

To swirl soap, pour most of the mixture into the mold, and then add a coloring agent to the remainder. Pour it on top of the rest, and use a wooden spoon or spatula and move it from one end of the container to the other. Continue doing this from different angles until you’ve criss-crossed the entire container, mixing the colored soap with the non-colored. As an alternate method, you can take around 1/4 of the mixture and add color to it, pour 1/2 of the non-colored mix into the container, top with 1/2 of the colored, the rest of the non, and finally the rest of the color. Swirl as above. You may also color both portions, so as to give contrasting colors to the finished product. Be sure to use non-toxic and non-staining materials for the colors.

For scented soaps, you may use small portions of essential oils or fragrance oils; be sure not to use too much, as the scent can easily become overpowering. To make pumice-type soaps for scrubbing, use poppy seeds or ground almond shells; dried and ground orange or lemon peel can also be added, to add a bit of citrus powder to the mix.

In the end, remember that you can experiment with the recipes as much as you like, adding and taking away ingredients until you’ve found the ones that are right for you. Have fun, and be careful when working with lye.

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